Types of HVAC Systems: Split AC, VRF, Heat Pumps & Ducted Systems — Which One's Right for You?

Overwhelmed by AC options? You're not alone. Walk into this market cold and you'll hear about splits, multi-splits, VRF, cassettes, ducted systems and heat pumps — often from someone trying to sell you whichever one they happen to stock. Here's how to pick the right system for your space, without the sales pitch.

Split Systems: The Default Choice for One or Two Rooms

A split system is the classic setup: one outdoor unit (housing the compressor) connected to one indoor unit (the wall-mounted part that blows air). Refrigerant pipes and cables run between them through a small hole in the wall.

Splits are the workhorses of domestic cooling. They're relatively quick to install, energy-efficient, and modern inverter-driven models are quiet enough for bedrooms. Most also work in reverse as air-to-air heat pumps, giving you efficient heating in winter for the same hardware.

Best for: a single living room, bedroom, home office, garden room or small shop. If you want to cool one or two spaces well, start here.

Multi-Split Systems: One Outdoor Unit, Several Rooms

A multi-split connects two to five indoor units to a single outdoor unit. Each room gets its own indoor unit and its own temperature control, but you only need one condenser outside — useful when outdoor space, planning constraints or aesthetics limit how many boxes you can hang on the wall.

The trade-off: if the outdoor unit fails, every room loses cooling at once, and installation design matters more because pipe runs are longer and more complex. Sizing needs to account for how many rooms will realistically run at the same time.

Best for: homes wanting cooling in 2–4 rooms, small offices, flats where the freeholder only permits one outdoor unit.

VRF Systems: The Commercial Heavyweight

VRF (Variable Refrigerant Flow) is the technology behind climate control in hotels, large offices and retail chains. One large outdoor system serves many indoor units — sometimes dozens — and continuously varies the amount of refrigerant sent to each one. Advanced heat-recovery VRF systems can cool one zone while heating another and recycle energy between them.

VRF is superbly efficient at scale and gives fine-grained zone control, but it's a premium investment that demands proper design, commissioning and maintenance. This is not a system to buy on price — a badly designed VRF install will underperform for its entire life.

Best for: large commercial premises, multi-floor offices, hotels, buildings with mixed heating/cooling demands.

Ducted Systems: Invisible Comfort for Whole Buildings

Ducted systems hide the indoor unit in a ceiling void or plant room and distribute air through concealed ducts to grilles in each room. The result is close to invisible — no wall units anywhere — with even, draught-free comfort.

The catch is that you need ceiling space for ductwork, which makes ducted systems easiest to fit during construction or major refurbishment. Retrofit is possible in some properties, but it's the most disruptive option on this list.

Best for: new builds, full refurbishments, larger homes and commercial spaces where aesthetics matter.

Heat Pumps: Heating and Cooling in One System

Air source heat pumps deserve their own category because they change the economics. Instead of generating heat by burning fuel, they move heat from outdoor air into your building — delivering 3–4 kWh of heat for every 1 kWh of electricity consumed. In summer, the cycle reverses and they cool.

Air-to-air heat pumps (essentially what a modern split system is) heat and cool the air directly. Air-to-water systems feed radiators and underfloor heating, replacing a gas boiler. With gas prices volatile and regulations tightening, heat pumps are increasingly the long-term answer for UK properties. We've covered the science in detail in our guide to how heat pumps work.

Best for: anyone thinking about year-round comfort and running costs, not just summer cooling.

Quick Comparison

Prices are indicative for the South East and vary with property, access and specification. An itemised quote is the only number worth planning around.

How to Actually Decide

• Count the rooms you'll genuinely use it in. One or two: split. Three or four: multi-split. Whole building: ducted or VRF.
• Think heating, not just cooling. If your boiler is over ten years old, a heat pump conversation now can save a second project later.
• Check your constraints. Listed building? Flat with a management company? Limited outdoor space? These often decide the system before preferences do.
• Insist on a proper heat-load calculation. Any installer quoting without surveying your space is guessing — and oversized systems cost more to buy and run.